Heating device

ABSTRACT

A heating apparatus for an exhaust train comprises a flow-conducting device for guiding an exhaust gas flow along a flow path; a burner that is arranged outside the flow-conducting device and that is configured to generate heating gases during the combustion of a fuel; and a supply device that is configured to supply the heating gases generated by the burner to the exhaust gas flow, which is guided through the flow-conducting device, via a heating gas inlet that is formed in a wall of the flow-conducting device. The supply device has a channel that is fastened to an outer side of the flow-conducting device in a manner covering the heating gas inlet and open towards it, wherein the channel extends along a peripheral direction running around the flow path and in so doing engages around the flow-conducting device while forming an interruption.

The present invention relates to a heating apparatus for an exhaust train, said heating apparatus comprising a flow-conducting device for guiding an exhaust gas flow along a flow path; a burner that is arranged outside the flow-conducting device and that is configured to generate heating gases during the combustion of a fuel; and a supply device that is configured to supply the heating gases generated by the burner to the exhaust gas flow, which is guided through the flow-conducting device, via a heating gas inlet that is formed in a wall of the flow-conducting device.

Such heating apparatus are, for example, used to heat exhaust gas catalytic converters and thereby to increase their efficiency. A fast heating of the exhaust gas catalytic converter is in particular important on a cold start of an internal combustion engine. The flow-conducting device can be a straight or an angled pipe, a funnel or the like that is integrated into an exhaust train upstream of an exhaust gas catalytic converter.

An uneven heating of the catalytic converter is detrimental to an optimum efficiency and can even lead to damage. In practice, it is, however, difficult to achieve a uniform mixing of the heating gases with the exhaust gas flow and a uniform heating of the total catalytic converter surface.

It is an object of the invention to provide a heating apparatus of the aforementioned kind that enables a particularly uniform heating of an exhaust gas catalytic converter with low pressure losses.

The object is satisfied, on the one hand, by a heating apparatus having the features of claim 1 and in particular in that the supply device has a channel that is fastened to an outer side of the flow-conducting device in a manner covering the heating gas inlet and open towards it, wherein the channel extends along a peripheral direction running around the flow path and in so doing engages around the flow-conducting device while forming an interruption.

In a heating apparatus designed in accordance with claim 1, the channel therefore only partly engages around the flow-conducting device. For example, the channel can be of a clasp-like, a clamp-like, or a claw-like design. This facilitates the production since a channel formed in this way is easier to manufacture and easier to attach to the flow-conducting device than, for example, a channel formed as a closed ring. Despite the interruption, the engaging-around channel is able to distribute the heating gases along the periphery of the flow-conducting device and is thus able to ensure a uniform mixing of the heating gases with the exhaust gases. The engaging-around design furthermore enables a particularly stable hold of the channel at the exhaust train.

The flow-conducting device defines the flow path based on its shape. The flow path does not necessarily have to be rectilinear, but can also extend in a curved manner.

The channel and/or the flow-conducting device is/are preferably sheet metal parts and/or is/are produced from a heat-resistant metal such as steel.

The channel is preferably completely open towards the flow-conducting device so that it can be used with different heating gas inlets. The channel is preferably sealed around the heating gas inlet. For example, the channel can be welded to the flow-conducting device along the border of the opening.

In accordance with an embodiment of the invention, the channel is formed in the manner of a half shell and/or is formed in one piece. This enables a particularly simple design.

The channel can in particular be a deep-drawn part. A deep-drawn component is much easier and less expensive to produce than, for example, a cast part.

A specific embodiment of the invention provides that the interruption extends over a peripheral region of 1% to 50%, in particular of 5% to 30%, of the total periphery of the flow-conducting device. This design has proved to be particularly favorable in practice since, despite the possible production as a half-shell component, the engagement around is relatively far-reaching and a good distribution of the heating gases in the exhaust train is thus possible.

The channel can have a supply opening that is connected to the burner and that is centrally arranged at the channel with respect to the extent of the channel in the peripheral direction. The supply opening can in particular be arranged disposed opposite the interruption. In this respect, the heating gases enter into two arms of the channel of equal length via the supply opening, from which a particularly uniform distribution results.

Alternatively, the channel can have a supply opening that is connected to the burner and that is arranged at an end region of the channel with respect to the extent of the channel in the peripheral direction. This design can, for example, be advantageous for certain applications due to installation space restrictions. The supply opening can generally also be arranged such that two arms of the channel of different lengths result.

The heating gas inlet can comprise a gap extending in the peripheral direction. Due to the gap, the heating gases are relatively widely distributed in the flowing exhaust gas, from which a good mixing of the gas flows results.

In accordance with a specific embodiment of the invention, the gap extends at least substantially along the total length of the channel. A particularly uniform heating of the exhaust gases is thereby achieved.

The initially described object is thereby also satisfied in that the supply device has a channel that is fastened to an outer side of the flow-conducting device in a manner covering the heating gas inlet and open towards it, wherein the channel extends along a peripheral direction running around the flow path, and wherein the heating gas inlet comprises a plurality of individual openings spaced apart from one another, as defined by claim 10.

The individual openings arranged at a spacing have the advantage that they enable a heating gas supply distributed along the periphery of the flow-conducting device, but reduce the stability of the flow-conducting device only insignificantly. An unwanted delay of the flow-conducting device in the region of the heating gas inlet is in particular avoided.

The heating gas inlet can comprise a regular hole row that extends in the peripheral direction along the total channel. A regular hole row requires only a small manufacturing effort and supports a uniform mixing of the heating gases with the exhaust gases. In principle, the heating gas inlet can, however, also comprise an irregular hole row in order, for example, to produce very specific inflow characteristics and/or to account for pressure differences in the channel. For example, the individual openings can be larger far away from a supply opening connected to the burner than adjacent to the supply opening. In other words, it can be advantageous that the size of the holes increases with the distance from the supply opening. The pressure loss that occurs along the channel can thereby be compensated. This means that, on a suitable dimensioning of the openings, essentially just as much heating gas enters the exhaust gas flow at the end of the channel or opposite the supply opening as at the start of the channel so that the mixing is particularly uniform.

Provision can be made that at least one individual opening is designed as an elongate hole or that all the individual openings are designed as elongate holes. Tests have shown that a uniform mixing of the heating gases with the exhaust gases is hereby promoted further.

Provision can be made that the elongate holes extend transversely to the flow path or that the elongate holes extend alternately longitudinally and transversely to the flow path. The shape, the length and the orientation of the elongate holes can be adapted to a specific application in this respect.

The elongate holes can have at least two different sizes. For example, large and small elongate holes can be arranged in an alternating manner. This opens up further adaptation possibilities.

In accordance with a further embodiment of the invention, the channel forms a closed ring. A distribution of the heating gases along the total periphery of the flow-conducting device is hereby achieved.

Further developments of the invention can also be seen from the dependent claims, from the description, and from the enclosed drawings.

The invention will be described in the following by way of example with reference to the drawings.

FIG. 1 is a simplified representation of an exhaust train section that is provided with a heating apparatus in accordance with the invention;

FIG. 2 is a perspective part representation of a heating apparatus in accordance with a first embodiment of the invention;

FIG. 3 shows a heating apparatus in accordance with a second embodiment of the invention;

FIG. 4 shows a heating apparatus in accordance with a third embodiment of the invention; and

FIG. 5 shows a heating apparatus in accordance with a fourth embodiment of the invention.

The exhaust train section 11 shown in FIG. 1 receives exhaust gases from an internal combustion engine, not shown, and supplies them to an exhaust gas catalytic converter 13. A flow-conducting device 15 arranged upstream of the exhaust gas catalytic converter 13 serves to guide an exhaust gas flow 16 along a flow path 18 that is straight here. The flow-conducting device 15 is part of a heating apparatus 17 that serves to heat the exhaust catalytic converter 13, in particular on a cold start of the internal combustion engine.

The heating apparatus 17 comprises a burner 19 that, as shown, is arranged outside the flow-conducting device 15 and that generates and discharges heating gases during the operation by a combustion of a fuel. A channel 20 receives the heating gases from the burner 19 via a supply line 21 and feeds the heating gases via a heating gas inlet 23 to the exhaust gas flow 16 that is guided through the flow-conducting device 15. Accordingly, the supply line 21 and the channel 20 form a supply device 26 for burner gases. The burner 19 is preferably arranged so close to the exhaust gas catalytic converter 13 that heat losses over the transport path are negligible.

FIG. 2 shows a first embodiment of a heating apparatus 17 in accordance with the invention without a burner and a supply line. As shown, the channel 20 extends along a peripheral direction 22 running around the flow path 18 and in so doing engages around the flow-conducting device 15 while forming an interruption 30. The channel 20 is substantially completely or continuously open towards the flow-conducting device 15 in the peripheral direction and is fastened, for example welded, to the outer side 35 of the flow-conducting device 15 along a border 33 of the opening. The channel 20 is preferably designed as a single-piece half-shell component.

In the embodiment shown in FIG. 2 , the heating gas inlet 23 is formed by a gap 27 formed in the wall 25 of the flow-conducting device 15. The gap 27 extends at least substantially along the total peripheral length of the channel 20. For stability reasons, the gap 27 is interrupted by a plurality of webs 28, of which only one is visible in FIG. 2 . However, these webs 28 do not impede the inflow of the heating gas over the peripheral region, which is covered by the channel 20, in a relevant manner. The provision of webs 28 is not absolutely necessary.

The connection in terms of flow of the burner 19 to the channel 20 takes place via a supply opening 37 that, in the embodiment shown in FIG. 2 , is centrally arranged at the channel 20 with respect to the extent of the channel 20. This means that, starting from the supply opening 37, the channel 20 has two channel arms 38, 39 of equal length and is shaped like a clasp.

In the embodiment of FIG. 2 , the flow path 18 is curved. Furthermore, the flow-conducting device 15 is widened in a funnel-like manner, that is, an exhaust gas inlet 40 is smaller than an exhaust gas outlet 41 of the flow-conducting device 15.

The embodiment of a heating apparatus 47 in accordance with the invention shown in FIG. 3 is similar in design to the heating apparatus 17 shown in FIG. 2 , wherein the heating gas inlet 53 is, however, not formed as a gap, but as a regular hole row 55. As shown, the hole row 55 extends in the peripheral direction 22 along the total channel 20 that is closed in the peripheral direction 22 in the example shown. However, said channel 20 can also have an interruption, if necessary. In the embodiment of FIG. 3 , the hole row 55 comprises elongate holes 57 that each extend transversely or obliquely to the flow path 18.

FIG. 4 shows a further embodiment of a heating apparatus 67 in accordance with the invention that in particular differs from the heating apparatus 17, 47 of FIGS. 2 and 3 in that the supply opening 37 is located at an end region 69 of the channel 80. That is, the supply opening 37 is arranged adjacent to the interruption 30. The channel 80 furthermore tapers towards the opposite end region 70. The pressure loss along the channel 80 can thereby be compensated.

In the embodiment shown in FIG. 4 , a receiver 75 for a sensor is located in the interruption 30. The overall length of the flow-conducting device 15 can thereby be kept short in the axial direction. A gap 27 is provided as the heating gas inlet 23 in the embodiment of FIG. 4 , as in the embodiment of FIG. 2 .

FIG. 5 shows an embodiment of a heating apparatus 77 in accordance with the invention in which the channel 90 does not have an interruption, but is designed as a closed ring. As in the embodiment of FIG. 3 , a hole row 55 is provided as the heating gas inlet 53. Said hole row 55 comprises elongate holes 57 that here extend alternately longitudinally and transversely to the flow path 18 and that are also alternately of a large and a small design.

An embodiment in which a heating gas inlet is provided with a plurality of columns or a plurality of hole rows is not shown. Furthermore, a heating gas inlet could also be provided that has both at least one gap 27 and at least one hole row 55.

Since the heating gases generated by the burner 19 enter the exhaust gas flow 16 in a manner distributed along the periphery of the flow-conducting device 15, a fast mixing of the heating gases with the flowing exhaust gases takes place and a uniform heating of the exhaust gas catalytic converter 13 thus takes place. Said exhaust gas catalytic converter 13 can thus be operated with a high degree of efficiency in different operating states of the internal combustion engine and is protected against damage by a local overheating. Since no components of the heating apparatus 17 project into the interior of the flow-conducting device, the pressure loss is low. Thus, the invention enables an improved purification of exhaust gases by simple means.

In general, channels with or without an interruption can be combined with openings of any desired design to meet the respective present requirements.

REFERENCE NUMERAL LIST

-   -   11 exhaust train section     -   13 exhaust gas catalytic converter     -   15 flow-conducting device     -   16 exhaust gas flow     -   17 heating apparatus     -   18 flow path     -   19 burner     -   20 channel     -   21 supply line     -   22 peripheral direction     -   23 heating gas inlet     -   25 wall     -   26 supply device     -   27 gap     -   30 interruption     -   33 border     -   35 outer side     -   37 supply opening     -   38 channel arm     -   39 channel arm     -   40 exhaust gas inlet     -   41 exhaust gas outlet     -   47 heating apparatus     -   53 heating gas inlet     -   55 hole row     -   57 elongate hole     -   67 heating apparatus     -   69 end region     -   70 end region     -   75 receiver     -   77 heating apparatus     -   80 channel     -   90 channel 

1-14. (canceled)
 15. A heating apparatus for an exhaust train, said heating apparatus comprising a flow-conducting device for guiding an exhaust gas flow along a flow path; a burner that is arranged outside the flow-conducting device and that is configured to generate heating gases during the combustion of a fuel; and a supply device that is configured to supply the heating gases generated by the burner to the exhaust gas flow, which is guided through the flow-conducting device, via a heating gas inlet that is formed in a wall of the flow-conducting device, wherein the supply device has a channel that is fastened to an outer side of the flow-conducting device in a manner covering the heating gas inlet and open towards it, wherein the channel extends along a peripheral direction running around the flow path and in so doing engages around the flow-conducting device while forming an interruption.
 16. The heating apparatus in accordance with claim 15, wherein the channel is completely open towards the flow-conducting device.
 17. The heating apparatus in accordance with claim 15, wherein the channel is formed in the manner of a half shell and/or is formed in one piece.
 18. The heating apparatus in accordance with claim 15, wherein the interruption extends over a peripheral region of 1% to 50% of the total periphery of the flow-conducting device.
 19. The heating apparatus in accordance with claim 18, wherein the interruption extends over a peripheral region of 5% to 30% of the total periphery of the flow-conducting device.
 20. The heating apparatus in accordance with claim 15, wherein the channel has a supply opening that is connected to the burner and that is centrally arranged at the channel with respect to the extent of the channel in the peripheral direction.
 21. The heating apparatus in accordance with claim 15, wherein the channel has a supply opening that is connected to the burner and that is arranged at an end region of the channel with respect to the extent of the channel in the peripheral direction.
 22. The heating apparatus in accordance with claim 15, wherein the heating gas inlet comprises a gap extending in the peripheral direction.
 23. The heating apparatus in accordance with claim 22, wherein the gap extends at least substantially along the total length of the channel.
 24. A heating apparatus for an exhaust train, comprising a flow-conducting device for guiding an exhaust gas flow along a flow path; a burner that is arranged outside the flow-conducting device and that is configured to generate heating gases during the combustion of a fuel; and a supply device that is configured to supply the heating gases generated by the burner to the exhaust gas flow, which is guided through the flow-conducting device, via a heating gas inlet that is formed in a wall of the flow-conducting device, wherein the supply device has a channel that is fastened to an outer side of the flow-conducting device in a manner covering the heating gas inlet and open towards it, wherein the channel extends along a peripheral direction running around the flow path, and wherein the heating gas inlet comprises a plurality of individual openings spaced apart from one another.
 25. The heating apparatus in accordance with claim 24, wherein the channel extends along a peripheral direction running around the flow path and in so doing engages around the flow-conducting device while forming an interruption.
 26. The heating apparatus in accordance with claim 24, wherein the heating gas inlet comprises a regular hole row that extends in the peripheral direction along the total channel.
 27. The heating apparatus in accordance with claim 24, wherein at least one individual opening is designed as an elongate hole or all the individual openings are designed as elongate holes.
 28. The heating apparatus in accordance with claim 27, wherein the elongate holes extend transversely to the flow path.
 29. The heating apparatus in accordance with claim 27, wherein the elongate holes extend alternately longitudinally and transversely to the flow path.
 30. The heating apparatus in accordance with claim 27, wherein the elongate holes have at least two different sizes.
 31. The heating apparatus in accordance with claim 24, wherein the channel forms a closed ring. 